CN102841021A - Low-temperature splitting tester for fiber asphalt mixture - Google Patents

Abstract

The invention relates to a fibrous asphalt mixture splitting test device, including a loading mechanism, a horizontal displacement measuring mechanism, a vertical displacement measuring mechanism, and a data acquisition and analysis system, which can accurately test asphalt mixture and fiber asphalt mixture specimens from The load, vertical deformation and horizontal deformation from loading to destruction, combined with the acquisition system, can easily obtain the full curve of splitting load-vertical deformation, splitting load-horizontal deformation and Poisson's ratio corresponding to different deformations, and the test efficiency High, high precision, low cost.

Description

Low temperature splitting test device for fiber asphalt mixture

technical field

The invention belongs to the technical field of engineering detection and test equipment, and relates to a test device for testing the splitting strength and deformation performance of fiber asphalt mixture.

Background technique

Asphalt mixture is the main paving material of high-grade highway pavement in my country. The strength and deformation performance of asphalt mixture at low temperature are the key technical indicators for evaluating its low temperature crack resistance, and are the basis for theoretical analysis and asphalt pavement structure design. In view of the many difficulties in directly testing the tensile strength and deformation of asphalt mixtures, the test procedure for asphalt and asphalt mixtures in my country's highway engineering JTJ 052-2000 adopts the test method of indirect tension (split). According to the provisions of this regulation, when performing asphalt mixture low-temperature splitting test, it is required to load along the radial direction of asphalt mixture cylindrical specimen (usually Marshall specimen) under certain low temperature conditions and a certain loading rate. During the loading process, the vertical deformation, horizontal deformation and corresponding load value of the specimen should be recorded at the same time, and the splitting tensile strength, failure strain, Poisson's ratio, stiffness modulus, etc. of the asphalt mixture specimen should be calculated from the measured results. parameter. Designing a reasonable and feasible splitting test device is crucial to obtaining these technical parameters accurately. Although the existing test regulations stipulate the splitting test method of asphalt mixture, the method only clearly stipulates the structure of the test piece layer, but does not specify the production of the entire splitting device, resulting in the actual application. The device used in the splitting test is difficult to accurately obtain the stress-strain curve when the asphalt mixture is split at low temperature, and it is not suitable to directly obtain the horizontal deformation of the specimen when it is damaged. Therefore, many tests do not test the horizontal deformation value, so that The low-temperature performance of the measured asphalt mixture cannot be correctly analyzed and evaluated.

The existing asphalt mixture low-temperature splitting tester (patent number CN1793829A) is mainly composed of a loading fixture and a horizontal displacement test fixture, and the device for measuring horizontal deformation includes a left fixture, a right fixture and a limit block. Wherein, the left clamp includes a left guide block, a left sliding insertion rod arranged on the left guide block, an elastic device arranged between the left guide block and the left sliding insertion rod; the right clamp includes a right guide block, a The right sliding insertion rod, the elastic device arranged between the right guide block and the right sliding insertion rod, and the limit block are arranged on the left sliding insertion rod or the right sliding insertion rod. Although the structure of the device can actually measure the horizontal deformation of the test piece in a small range where the test piece is in the elastic section, as the deformation increases, the data on the side will no longer reflect the real horizontal deformation of the test piece, let alone obtain The real load-deformation curve of the test piece is because the horizontal center position of the test piece will gradually decrease with the increase of deformation, and the horizontal displacement meter in this patent cannot coordinate with the deformation at the diameter position of the test piece in the horizontal direction, so During the splitting process, the contact point between the test top bead of the horizontal displacement meter and the diameter of the specimen at the level will be separated as the deformation of the specimen increases, resulting in the result that the greater the deformation capacity of the specimen, the greater the test error, especially for those with Fibrous asphalt mixture with greater low-temperature deformability. At the same time, in most laboratories, general-purpose equipment (such as environmental chambers, universal testing machines, etc.) is already available, and in this case there is no need to purchase a special asphalt mixture splitting test machine. To this end, a splitting device that is economical, durable, easy to operate and can accurately test the low-temperature performance parameters of asphalt mixtures, especially the low-temperature splitting failure parameters of fiber asphalt mixtures with large low-temperature deformation capacity, has been developed. Not only can it provide accurate data for the structural design and theoretical analysis of the new asphalt mixture pavement, but it can also make full use of existing equipment resources and reduce repeated investment.

Contents of the invention

The present invention provides a fibrous asphalt mixture splitting test device, which can accurately test the load, vertical deformation and horizontal deformation of the asphalt mixture and fiber asphalt mixture specimens from loading to destruction, combined with the collection system can be convenient The full curves of splitting load-vertical deformation, splitting load-horizontal deformation and Poisson's ratios corresponding to different deformations are obtained, and the test efficiency is high, the precision is high, and the cost is low.

Technical solution: A low-temperature splitting test device for fiber asphalt mixture, including a loading mechanism, a horizontal displacement measuring mechanism, a vertical displacement measuring mechanism, and a data acquisition and analysis system; wherein, the loading mechanism includes upper and lower pressure plates and vertical guide rods The formed frame, the upper end of the vertical guide rod is fixed on the lower side of the upper platen, the lower end of the vertical guide rod protrudes from the guide hole provided on the lower platen, and the pressure testing machine applies pressure to the upper and lower platens to make them slide relative to each other; A load sensor is arranged at the center of the lower side of the upper platen, and the lower side of the load sensor is connected to a longitudinal upper arc-shaped bead through a connecting piece, and a longitudinal lower arc-shaped bead is arranged at the center of the upper side of the lower platen. , Corresponding to the lower arc bead; one side of the upper arc bead is connected with a vertical displacement meter top plate, a pole is vertically fixed on the lower pressure plate, and a vertical displacement meter is installed on the pole. The measurement of the vertical displacement meter The end is used in conjunction with the top plate of the vertical displacement meter; a horizontal displacement meter frame is arranged in the middle area of the upper and lower arc-shaped bead, and asymmetric vertical clamping rods are respectively installed on the left and right sides of the frame, and the test piece It is located between the two clamping rods; the vertical clamping rod on the left is fixedly installed with the frame, and a guide rod is fixed horizontally on the back of the vertical clamping rod on the right. The end of the guide rod is connected with the top plate for horizontal displacement testing. There is a sliding guide rail in the middle of the rod, and a pressure spring is connected between the sliding guide rail and the adjacent vertical clamping rod. One side of the sliding guide rail is fixed on the frame, and a horizontal displacement gauge is installed on the frame at the same time. The measuring end of the gauge is used in conjunction with the horizontal displacement test top plate; the signal lines of the load sensor, vertical displacement gauge and horizontal displacement gauge are connected to the input end of the computer through the A/D converter.

The lower surface of the lower platen is provided with a positioning screw sliding guide groove, and a positioning screw is installed in the guide groove. The positioning screw is adjusted according to the size of the lower platen of the pressure testing machine, so that the clamp is fastened to the on the testing machine.

A spherical indenter is arranged at the center of the upper end surface of the upper pressing plate, and the spherical indenter is used as a direct contact part of the pressure testing machine.

Pulleys are installed at the bottom of the horizontal displacement frame.

A height adjustment knob is threadedly connected to the lower end of the vertical guide rod between the upper and lower pressing plates.

The inner sides of the vertical clamping rods on the left and right sides are triangular rib structures.

A pull ring is also arranged at the end of the guide rod on the back side of the vertical clamping rod on the right side.

Beneficial effects: (1) The positioning and tightening screws of the lower platen facilitate the accurate installation and positioning of the splitting device on the lower platen of the testing machine, avoiding wasting time due to repeated centering and adjustment of the splitting device, which is necessary for asphalt with strict temperature requirements The test of the mixture specimen is particularly important to ensure the accuracy of the test results; the adjustment function of the fixing screw of the lower platen enables the splitting device to be applicable to the lower platens of different sizes of the testing machine within a certain range, so that it can make full use of Existing instruments and equipment in the laboratory can expand their scope of use, reduce repeated investment, and save resources.

(2) The reverse installation of the vertical displacement meter and the horizontal displacement meter enables the displacement meter to perform pop-up measurement of the deformation of the test piece, avoiding the traditional pressure-back measurement method that may easily cause the displacement meter to be damaged due to misoperation or excessive deformation of the test piece. crushed defect.

(3) The setting of the rotating shaft of the upper arc-shaped bead ensures that the test piece is evenly stressed and avoids the adverse effects of bias pressure and test piece misalignment on the test results.

(4) The setting of the limit protrusion on the inner side of the lower arc-shaped bead is conducive to the accurate placement of the test piece, so that the upper and lower arc-shaped bead can be just pressed on the test piece.

(5) The vertical setting of the specimen clamping rod ensures that the clamping rod can hold the diameter position of the specimen well during the whole splitting test process, avoiding the gap caused by the central position of the specimen in the traditional test method. Reduce the defect that the top ball of the displacement gauge leaves the position of the horizontal diameter of the test piece prematurely, so as to ensure the accuracy of the measured results.

(6) The linear design of the contact point between the specimen clamping rod and the specimen ensures that the specimen and the clamping rod can be in good contact during the entire horizontal deformation test process of the specimen. The rods are arranged in a three-point arrangement horizontally to ensure the accuracy of the horizontal deformation test results.

(7) The pulley at the bottom of the specimen clamping rod can reduce the restriction of the clamping rod on the deformation of the specimen and ensure the accuracy of the measured results.

(8) The square design of the cross-section of the horizontal sliding guide rod and the horizontal sliding guide rail ensures that the three specimen clamping rods always clamp the specimen in the same direction, thus obtaining accurate horizontal deformation test results.

(9) The data acquisition and analysis system can record the data during the test in real time and analyze and process the test results to give reasonable parameters.

(10) This splitting test device measures the deformation of the specimen through the displacement sensor, especially the horizontal deformation, avoiding the disadvantages of cumbersome operation and high cost caused by the method of pasting strain gauges, especially for fiber asphalt with large deformation In the test of concrete splitting performance, since the strain gauge may be broken after the peak load, the test cannot be continued. Ideal test results can be obtained by using this splitting device, so the device is easier to popularize and implement.

Description of drawings

Fig. 1 is the structural representation of embodiment 1 of the present invention;

Fig. 2 is A-A sectional schematic diagram among Fig. 1;

Fig. 3 is B-B sectional schematic diagram among Fig. 1;

Figure 4 is the splitting load-vertical deformation curve and load-horizontal deformation curve of asphalt concrete under the condition of 10°C;

Figure 5 shows the splitting load-vertical deformation curve and load-horizontal deformation curve of asphalt concrete at 30°C.

Detailed ways

The present invention will be described in further detail below according to the drawings and embodiments, but the present invention is not limited to the following embodiments.

Example 1. Referring to Fig. 1, Fig. 2 and Fig. 3, the asphalt mixture low-temperature splitting test device of this embodiment is composed of a spherical indenter 1, an upper pressing plate 2, a load sensor 3, an upper arc-shaped bead connector 4, and an upper arc-shaped bead. 5. Loading guide rod 6, test piece 7, lower arc bead 8, lower pressing plate 9, positioning screw sliding guide groove 10, lower pressing plate positioning tightening screw 11, height adjustment knob 12, specimen clamping rod 13, pulley 14 , Horizontal displacement meter frame 15, spring 16, guide hole 17, horizontal sliding guide rail 18, horizontal sliding guide rod 19, pull ring 20, horizontal displacement test top plate 21, horizontal displacement meter locking card 22, horizontal displacement meter 23, vertical displacement Meter pole 24, vertical displacement meter top plate 25, vertical displacement meter locking card 26, vertical displacement meter 27, computer 28, A/D converter 29 are connected to form.

The spherical indenter 1 of the loading structure of this embodiment is an element that directly bears the load transmitted from the testing machine, and continues to transmit the load evenly to the load sensor 3 through the upper platen 2, and the load sensor 3 continues to transmit the load to it through the wire connection. The upper arc bead connector 4, the upper arc bead connector 4 is connected with the upper arc bead 5 as an axis, so as to ensure that the test piece is evenly stressed. The loading guide rod 6 is an element to ensure that the upper arc-shaped bead 5 and the lower arc-shaped bead 8 are vertically centered during the loading process. 9 moves upward along the loading guide rod 6 through the guide hole 17, so that the test piece 7 placed on the lower arc-shaped bead 8 gradually approaches the upper arc-shaped bead 5 to be stressed. The lower arc-shaped bead 8 is fixed at the center of the lower platen 9, and is a component for positioning and loading the test piece 7. Before the test, the test piece 7 is placed on the lower arc-shaped bead 8, and passed through one end The bulge is precisely positioned, and the split loading mode is ensured by the action of the upper and lower arc-shaped bead. The lower pressing plate 9 is the supporting and loading element of the whole device. When using the asphalt mixture splitting test fixture of the present invention, the lower pressing plate 9 is first placed on the lower pressing plate of the testing machine so that the spherical indenter 1 is aligned with the top of the pressure testing machine. At the center of the pressure plate, slide the lower pressure plate along the positioning screw sliding guide groove 10 and tighten the screw 11 to fix the lower pressure plate 9 of the fixture on the lower pressure plate of the pressure testing machine. Turn the height adjustment knob 12 to make the upper arc-shaped bezel 5 and the lower There is enough space to place the test piece 7 between the curved beading bars 8 .

In this embodiment, the horizontal displacement measuring jig consists of a specimen clamping rod 13, a pulley 14, a horizontal displacement gauge frame 15, a spring 16, a horizontal sliding guide rail 18, a horizontal sliding guide rod 19, a pull ring 20, a horizontal displacement gauge top plate 21, and a horizontal displacement gauge. Displacement meter locking card 22 and horizontal displacement meter 23 are connected to form. The horizontal plane of the horizontal displacement meter frame 15 is U-shaped with an opening facing inward. Its two limbs are asymmetrical, the left limb is slightly longer, and two specimen clamping rods 13 are consolidated in the vertical direction. The bottom end of the specimen clamping rod 13 passes through the shaft. A pulley 14 is connected to reduce the resistance of the clamping rod to the test piece when the test piece is deformed. The right joint limb of horizontal displacement gauge frame 15 is slightly shorter, and its right side is provided with cross-section and is the horizontal sliding guide rail 18 of square, is the horizontal sliding guide rod 19 of square cross section equally and passes horizontal sliding guide rail 18, both adopt clearance fit, and the clearance in the gap Set lubricant. The side of the horizontal sliding guide rod 19 close to the test piece is consolidated with the vertical specimen clamping rod 13, and a spring 16 is arranged between the specimen clamping rod 13 and the horizontal sliding guide rail 18, and the spring 16 pushes the right specimen clamping rod to make the The test piece is clamped. Horizontal sliding guide rod 19 passes through the right end of horizontal sliding guide rail 18 and draw ring 20 is set, and the inboard of draw ring connects horizontal displacement test top board 21, and the right joint limb inside upper side of horizontal displacement meter frame 15 corresponding with horizontal displacement test top board 21 Consolidate the horizontal displacement meter locking card 22, and the horizontal displacement meter 23 is fixed on the horizontal displacement meter locking card 22. When the test piece is deformed, the left and right test piece clamping rods are pushed to make relative movements, and the test piece clamping rod passes through each component. The transfer finally makes the horizontal displacement test top plate 21 and the horizontal displacement gauge locking clip 22 move relative to each other, so that the horizontal displacement gauge 23 can measure the horizontal deformation of the test piece. The vertical setting of the specimen clamping rod 13 ensures that the clamping rod can hold the diameter position of the specimen well during the whole splitting test process, avoiding the decrease of the central position of the specimen in the traditional test method. The defect where the top ball of the displacement gauge breaks away from the position of the horizontal diameter of the specimen prematurely. The horizontal section of the test piece clamping rod 13 close to the test piece is triangular, and the contact point with the test piece is the apex of the triangular section to facilitate full contact with the test piece. The three test piece clamping rods are also triangular in horizontal direction, so that Ensure the accuracy of the measured horizontal deformation. The pulley is connected to the bottom end of the specimen clamping rod, and is used to reduce the resistance when the specimen clamping rod moves relative to the horizontal direction, thereby reducing the test error of horizontal deformation.

In this embodiment, the vertical displacement measurement jig is composed of a vertical displacement gauge support rod 24 , a vertical displacement gauge top plate 25 , and a vertical displacement gauge locking clip 26 . The vertical displacement meter pole 24 is vertically fixed on the outer edge of the lower pressure plate 9, the vertical displacement meter locking clip 26 is fixed on the top of the vertical displacement meter pole, and the vertical displacement meter top plate 25 is fixed on the outside of the upper arc-shaped bead 5 , the vertical displacement meter 27 is installed on the vertical displacement meter locking card 26, and the relative motion of the vertical displacement meter top plate 25 and the vertical displacement meter locking card 26 after the test piece 7 is split makes the vertical displacement meter 27 measure the vertical position of the test piece. Deformation amount. The method of pop-up testing the deformation of the test piece by the displacement meter avoids the defect that the displacement meter is easily crushed due to misoperation or excessive deformation of the test piece in the traditional pressure-back measurement method.

The data acquisition and analysis system in this embodiment is composed of a load sensor 3, a horizontal displacement meter 23, a vertical displacement meter 27, an A/D converter and a computer connection. The load sensor 3 converts the received load signal of the asphalt mixture test piece into an electrical signal and transmits it to the A/D converter 29 through the data cable, and the horizontal displacement meter 23 converts the received horizontal load signal of the asphalt mixture test piece. The deformation signal is converted into an electrical signal and transmitted to the A/D converter 29 through the data cable, and the vertical displacement meter 27 converts the received vertical deformation signal of the asphalt mixture specimen into an electrical signal and transmits it to the A/D through the data cable. The converter 29, the A/D converter 29 converts the input electrical signal into a digital signal and inputs it to the computer 28, and the computer 28 can display the load and displacement signals during the test from time to time through the control and analysis software, and analyze the results The technical parameters such as splitting tensile strength, failure strain, Poisson's ratio, and failure modulus of asphalt mixture specimens are given.

other embodiments. Change the connection mode and specific specifications and structure of the spherical indenter 1 and the upper pressure plate 2, change the connection mode and specific specifications and structure of the upper arc bead 5, the upper arc bead connector 4 and the load sensor 3, and change the vertical displacement gauge lock. The quantity, specific specifications and structure of the clamping clamp 26 and the clamping clamp 22 of the horizontal displacement meter, the quantity and the specific specifications and structure of the specimen clamping rod 13, and the connection mode, specific specifications and structure of the frame 15 of the horizontal displacement gauge are changed. Multiple embodiments can be formed, all of which are common variations of the present invention, and will not be described in detail here.

Test verification

A new building material and structure research center of a university tested the splitting strength and deformation performance of fiber asphalt concrete specimens by using the fiber asphalt mixture splitting test device of the present invention, and obtained satisfactory results. In this example, the mineral material gradation adopts the median value of the densely graded asphalt concrete gradation range stipulated in the specification JTG F40-2004. The particle size above 1.18mm is porous basalt, and the particle size below 1.18mm is limestone. The filler is ground limestone powder. The asphalt used is heavy traffic AH-70, mixed with 0.2% polyester fiber by mass of asphalt concrete. The tests were carried out at 10°C and 30°C respectively. The splitting load-vertical deformation curve and load-horizontal deformation curve of asphalt concrete with 0.2% polyester fiber content are shown in Figure 4 and Figure 5, and the test results are shown in Table 1.

Table 1

temperature/℃ Vertical deformation/mm Horizontal deformation/mm Load/kN Splitting strength/MPa A Poisson's ratio u failure strain/uε Stiffness modulus/MPa 10 2.09 0.306 31.19 3.09 6.83 0.253 6363 839 30 6.33 1.314 4.44 0.44 4.82 0.469 26528 39

It can be seen that the splitting strength and deformation value, especially the horizontal deformation value, of the asphalt concrete specimen under different test conditions can be easily obtained by using the asphalt mixture splitting test device of the present invention.

Claims (7)

1. fiber asphalt compound low temperature cracking test device is characterized in that: comprise that mechanism is measured in load maintainer, horizontal shift and mechanism is measured in perpendicular displacement, and the data collection and analysis system; Wherein, Add the framework that load mechanism comprises that upper and lower pressing plate and vertical guide pole form; The upper end of vertical guide pole is fixed on the top board downside, and stretch out in the pilot hole of lower platen setting the lower end of vertical guide pole, and pressure testing machine is exerted pressure to upper and lower pressing plate both are slided relatively; Center at the top board downside is provided with load transducer; The downside of load transducer is gone up the arc press strip longitudinally and is connected with one through web member; Be provided with arc lower press strip longitudinally in the center of lower platen upside, said upper and lower arc press strip is corresponding; Side at last arc press strip is connected with the vertical displacement meter top board, and vertical fixing pole is equipped with vertical displacement meter on the pole on said lower platen, and the measurement termination of this vertical displacement meter and said vertical displacement meter top board are used; Be provided with the horizontal displacement meter framework at upper and lower arc press strip zone line, the and arranged on left and right sides of this framework is separately installed with asymmetric vertical supporting rod, and test specimen is between two supporting rods; Wherein the vertical supporting rod in left side and frame fixation are installed; A guide pole of vertical supporting rod back side crosswise fixed on right side, this guide pole end are connected with horizontal shift test top board, and this guide pole middle part is provided with rail plate; Be connected with pressure spring between rail plate and the adjacent vertical supporting rod; Said rail plate one side is fixed on the said framework, and horizontal displacement meter is installed on framework simultaneously, and the measurement termination of this horizontal displacement meter and said horizontal shift test top board are used; The signal wire of said load transducer, vertical displacement meter and horizontal displacement meter is connected with the computing machine input end through A/D converter.

2. fiber asphalt compound low temperature cracking test device according to claim 1; It is characterized in that: the lower surface at lower platen is provided with the dog screw sliding guide groove; Coupling is equipped with and locatees the screw of screwing in this guide groove; This location screw of screwing is adjusted according to the lower platen size of pressure testing machine, and said anchor clamps are anchored on the testing machine.

3. fiber asphalt compound low temperature cracking test device according to claim 1, it is characterized in that: the center, upper surface of top board is provided with spherical indenter, and this spherical indenter is as the direct contact component of pressure testing machine.

4. fiber asphalt compound low temperature cracking test device according to claim 1, it is characterized in that: the bottom of said horizontal shift framework is equipped with pulley.

5. fiber asphalt compound low temperature cracking test device according to claim 1, it is characterized in that: the lower end screw thread of the vertical guide pole between upper and lower pressing plate is connected with height adjustment knob.

6. fiber asphalt compound low temperature cracking test device according to claim 1 is characterized in that: the inboard of the vertical supporting rod of and arranged on left and right sides is a triangle rib structure.

7. fiber asphalt compound low temperature cracking test device according to claim 1 is characterized in that: the guide pole end at the vertical supporting rod back side, right side also is provided with draw ring.

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